"Each player can only have a single race in Decline on the map at any given time. If the player still has tokens from an earlier in Decline race left on the map, those are all immediately removed from the map and placed back in the storage tray, before flipping the new tokens into Decline."

So it sounds like you'd get to keep your in decline Trolls on the map to me. Weird situation though... I've played a lot and never had a race completely obliterated off the map.

"Each player can only have a single race in Decline on the map at any given time. If the player still has tokens from an earlier in Decline race left on the map, those are all immediately removed from the map and placed back in the storage tray, before flipping the new tokens into Decline."

So it sounds like you'd get to keep your in decline Trolls on the map to me. Weird situation though... I've played a lot and never had a race completely obliterated off the map.

I'm afraid that's not how it works. You can only keep one race in Decline at a time, but they have to be in order, so your Trolls would all be removed from the board and your Sorcerers would be your race in Decline, even though there aren't any on the board.